Vacuum wound dressing

ABSTRACT

Provided, in one embodiment, is a vacuum wound dressing for covering a wound bed comprising: a wound contact layer comprising a fibrous blend or fibrous material that forms a cohesive gel when wetted by wound exudate; a source of vacuum situated to be separated from the wound bed by the wound contact layer; and a vacuum sealing layer covering the wound contact layer and adapted to retain relative vacuum in the wound contact layer, wherein (i) the dressing is essentially missing a non-gelling, foam layer in which the source of vacuum is situated or (ii) the vacuum sealing layer comprises as an outer layer a foam layer.

This application claims the priority of U.S. Provisional Application No.60/625,488, filed Nov. 5, 2004.

The present invention relates to methods, devices and kits for treatinga wound with a dressing and vacuum.

Vacuum has been used to increase blood flow to wound tissue and toremove exudate from the wound site. It is believed that it has not beenrecognized that such methods can be effectively combined withgel-forming wound care products placed against the wound to which vacuumis applied.

SUMMARY OF THE INVENTION

Provided, in one embodiment, is a vacuum wound dressing for covering awound bed comprising: a wound contact layer comprising a fibrous blendor fibrous material that forms a cohesive gel when wetted by woundexudate; a source of vacuum situated to be separated from the wound bedby the wound contact layer; and a vacuum sealing layer covering thewound contact layer and adapted to retain relative vacuum in the woundcontact layer, wherein (i) the dressing is essentially missing anon-gelling, foam layer in which the source of vacuum is situated or(ii) the vacuum sealing layer comprises as an outer layer a foam layer.

Provided, in another embodiment, is a vacuum wound care modulecomprising: an fluid reservoir; a pump module fluidly connected to theirrigation reservoir and adapted for pumping fluid out of the fluidreservoir; a venturi vacuum fitting fluidly connected to the pump moduleand having a vacuum outlet and a fluid outlet; a fluid connection fromthe fluid outlet to the fluid reservoir; a trap reservoir fluidlyconnected to the vacuum outlet; and a second fluid connection that is(i) adapted to be fitted with a wound dressing to provide vacuum andallow removal of wound exudate or (ii) fitted to such a wound dressingsuch that, when the wound dressing is employed, it provides vacuum andallows removal of wound exudate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a shows a top view of separated products used in an illustrativeembodiment of the invention.

FIG. 1 b shows a side view of the illustrative embodiment.

FIG. 2 illustrates a side view of another illustrative embodiment.

FIG. 3 illustrates a composite of a wound care product similar to thatof FIGS. 1 a and 1 b, but further including a source of irrigationfluid.

FIG. 4 illustrates a vacuum device for use in wound care.

DETAILED DESCRIPTION OF THE INVENTION

The outer dressing used in the vacuum method can include a vacuumsealing outer layer that is film layer 11, and a foam layer 12. Asillustrated in FIGS. 1 a and 1 b, a vacuum source connector 21 (e.g.,silicone tubing) can be slotted through film layer 11 and foam layer 12,and sealed with another adhesive film 41. Film 41 can be, for example,the Opsite™ film dressing from Smith & Nephew (Cambridge, UnitedKingdom). The vacuum permeable foam layer 12 is separated from directcontact with the wound by wound contact layer 31.

As illustrated, the source of vacuum (illustrated as tubing) isfavorably separated from the wound by a wound contact layer, or aportion of a wound contact layer.

As illustrated in FIG. 2, the outer layer of the vacuum sealing layercan be foam layer 312, with the porosity of the foam layer selectedretain a portion of the vacuum at the wound site. Foam layer 312 isseparated from direct contact with the wound by wound contact layer 331.Vacuum source connector 321 can be slotted through foam layer 312.

The vacuum sealing layer can be, for example, a film layer alone (seeFIG. 3, discussed below), or a foam layer alone (see FIG. 2).

A foam layer can be provided by the foam layer of the Versiva® dressingavailable from ConvaTec (Skillman, N.J.).

The wound contact layer is, for example, a fibrous blend or fibrousmaterial (e.g., non-woven) that forms a cohesive gel when wetted withwound exudate. Such a fibrous material can be provided, for example, bythe wound contact layer of the Versiva® dressing (ConvaTec, Skillman,N.J.) or by a fibrous mat of sodium carboxymethylcellulose. A fibrousmat of sodium carboxymethylcellulose is available as AQUACEL® dressingfrom ConvaTec, as is a similar dressing further including silver. Otherexemplary wound contact layers are provided by Medicel™, Carboflex™(which provides an odor absorbent layer with fibrous material forwicking liquid away from the odor absorbent), Hyalofill™ (forming ahyaluronic acid-rich fibrous gel) or Kaltostat™ (containing alginate)dressings from ConvaTec.

The vacuum sealing layer serves to limit loss of reduced pressure suchthat a therapeutically useful degree of reduced pressure pertains at thewound site. Loss of reduced pressure (through the vacuum sealing layer)can be significant if compensated by the source of vacuum. It will berecognized the “vacuum” refers to reduced pressure relative toatmospheric pressure. The vacuum source provides a sufficient reductionin pressure such that a therapeutically useful degree of reducedpressure pertains at the wound site.

The wound contact layer can be selected to be effective to adhere thedressing to the wound site, even in the absence of vacuum, and to retainadhesiveness even as it is saturated with exudate liquid. Or, adhesioncan be provides at the peripheries of the wound dressing.

As illustrated in FIG. 3, the vacuum wound dressing can be used with afluid source connector 141 (here illustrated as a tube). The fluid canbe, for example, an irrigating fluid, such as saline or a salinesubstitute, and can include an anti-infective. The irrigating fluid canbe pumped to the wound bed, or drawn by the relative vacuum conveyed byvacuum source connector 121 (and sufficiently retained by vacuum sealinglayer 111).

In certain embodiments, the wound care dressing(s) used with vacuumprovide vacuum sealing layers with maximum pores of greater than 100micron pore size.

As illustrated in FIG. 4, a vacuum wound care module can be used toprovide vacuum and, optionally, irrigation fluid to a wound. The modulecan be scaled as a bedside unit, or miniaturized such that it can, forexample, be adhered or otherwise affixed near the wound site on apatient. In the illustrated embodiment, there are a reservoir 251, pumpmodule 252, venturi vacuum unit 253, optional diverting valve 254, andtrap reservoir 255. Fluid connectors 261, 262, 263, 264 and 265, vacuumsource connector 121, and fluid source connector 141 make fluidconnections as illustrated. The reservoir 251 provides fluid (i) to movethrough the venturi vacuum unit 253 to generate vacuum and (ii),optionally, provide irrigating fluid for the wound. If the fluid of thereservoir 251 is to provide irrigating fluid, the fluid is physiologicalsaline or saline substitute suitable for irrigating a wound.

The pump module 252 can be the mechanical pieces that provide pumping,with or without the components that provide motive force or pumping. Forexample, the pump module 252 can be adapted to couple with a motor toactivate the pump parts, or the pump module 252 can be adapted to beengaged by external electromagnet(s) to activate the pump parts. Theventuri vacuum unit 253 will typically have a region in which itsinternal diameter expands to increase the speed of fluid flow (from theinlet 253A to the fluid outlet 253B), thereby reducing pressureaccording to Bernoulli's Principle and providing vacuum at vacuum outlet253C.

Optional diverting valve 254 typically has two operating positions, eachadapted to allow flow in the “pump circuit” from the reservoir, throughthe venturi vacuum unit, and returning to the reservoir. One of theoperating positions additionally diverts an amount of flow suitable toprovide irrigation fluid to the wound. To at least a certain extent,back pressure from the flow pathway to the wound can help regulate therate of this diverted flow.

Trap reservoir 255 is situated to collect wound exudate and usedirrigating fluid before the vacuum draws such spent fluid into the pumpcircuit. Additional trap reservoirs, and/or sterile filters, can beplaced to limit any potential contamination of the pump circuit. Thevarious fluid conduits of the vacuum wound care module can incorporatecheck valves to help assure that there is no significant flow in anunintended direction. For example, such check valves can prevent flow ofreservoir fluid out the vacuum outlet 253C should the pump circuit betemporarily blocked, such as when the diverting valve is switched fromone position to the other.

Definitions

The following terms shall have, for the purposes of this application,the respective meanings set forth below.

-   -   non-gelling, foam

A non-gelling, foam is a material that does not gel to a functionallysignificant extent, and is sufficiently porous to move fluid bycapillary action.

Publications and references, including but not limited to patents andpatent applications, cited in this specification are herein incorporatedby reference in their entirety in the entire portion cited as if eachindividual publication or reference were specifically and individuallyindicated to be incorporated by reference herein as being fully setforth. Any patent application to which this application claims priorityis also incorporated by reference herein in the manner described abovefor publications and references.

While this invention has been described with an emphasis upon preferredembodiments, it will be obvious to those of ordinary skill in the artthat variations in the preferred devices and methods may be used andthat it is intended that the invention may be practiced otherwise thanas specifically described herein. Accordingly, this invention includesall modifications encompassed within the spirit and scope of theinvention as defined by the text in the Figures.

1. A vacuum wound care module comprising: a fluid reservoir; a pumpmodule fluidly connected to the fluid reservoir and adapted for pumpingfluid out of the fluid reservoir; a venturi vacuum fitting fluidlyconnected to the pump module and having a vacuum outlet and a fluidoutlet; a fluid connection from the fluid outlet to the fluid reservoir;a trap reservoir fluidly connected to the vacuum outlet; and a secondfluid connection that is one of: (a) fluidly connected to the trapreservoir and (i) adapted to be fitted with a wound dressing to providevacuum and allow removal of wound exudate or (ii) fitted to such a wounddressing such that, when the wound dressing is employed, it providesvacuum and allows removal of wound exudate, or (b) adapted to be fluidlyconnected to the trap reservoir and fitted to such a wound dressing suchthat, when the wound dressing is employed, it provides vacuum and allowsremoval of wound exudate.
 2. The vacuum wound care module of claim 1,wherein the second fluid connection is according to (a).
 3. The vacuumwound care module of claim 1, wherein the second fluid connection isaccording to (b).
 4. The vacuum wound care module of claim 1, furthercomprising: a diverting valve situated in the first fluid connection,the valve operating between (i) a position that directs fluid from thefluid outlet and the fluid reservoir and (ii) a position that directs amajor portion of fluid from the fluid outlet and the fluid reservoir anda minor portion to a third fluid connection; and the third fluidconnection that is one of (A) fluidly connected to the diverting valveand (i) adapted to be fitted with a wound dressing to provide fluid tothe wound or (ii) fitted to such a wound dressing such that, when thewound dressing is employed, it provides such fluid, or (B) adapted to befluidly connected to the diverting valve and fitted to such a wounddressing such that, when the wound dressing is employed, it providessuch fluid.
 5. The vacuum wound care module of claim 4, wherein thethird fluid connection is according to (A).
 6. The vacuum wound caremodule of claim 4, wherein the third fluid connection is according to(B).
 7. The vacuum wound care module of claim 1, wherein the wounddressing includes a wound contact layer comprising a fibrous blend orfibrous material that forms a cohesive gel when wetted by wound exudatein use.